On April 1, Kevin, Petra, and Pierre worked at the Ridge Lab while Darby worked in 0PAL. Petra made MIR FTIR measurements and finalized data backup and email systems, finished network mapping of the IR lab, and prepared the instrument for remote operation—that is, disconnected the coolant system used for the internal lamp, set up the FTIR spectrometer in the NIR configuration, and stored the KBr beamsplitter in its sealed container with fresh desiccant to keep it from being exposed to moisture. Kevin finished up network mapping the UV-Vis lab and helped Pierre dismantle and pack up the radio antenna on the Ridge Lab rooftop for the next campaign.

The UT-GBS spectrometer and tracker laptops had some trouble with the network, which posed a problem because the laptops need to work together to point the tracker mirrors when making measurements to guide the light that comes through the rooftop dome into the spectrometer. On April 2, Kevin worked on troubleshooting those issues. On the same day, Petra worked on MIR FTIR measurements and on tidying up the lab. She also arranged for equipment to be brought up on the next campaign to “pump down” the dewars of the infrared detectors, a process that helps to maintain their vacuum systems, as the liquid nitrogen hold time was less than it should be during this campaign. This maintenance will help ensure that on future campaigns the MIR measurements can be performed with the detectors remaining cool for the expected 24 hours.

April 3 was a sunny, cold day and we worked up to the last minute, finishing mounting webcams in 0PAL to be able to check on the Pandora and on the E-AERI instruments from afar. We said good-bye and thank-you to the staff at the Weather Station, then loaded up our luggage in the back of the CANDAC truck and drove up to the runway to meet the plane. The team helped unload the station’s fresh food supply for the next month, before boarding the produce charter plane to Yellowknife. After an overnight stay in Yellowknife, we made our way back to Toronto with a lay-over in Edmonton. The team made it home to Toronto on April 4.

With the close of the 2025 spring-time Canadian Arctic ACE/OSIRIS Validation Campaign, we would like to express our deep appreciation to the staff of ECCC's Eureka Weather Station whose on-site support was vital to the success of our campaign. We would also like to thank the Canadian Space Agency, Environment and Climate Change Canada, NSERC, the Northern Scientific Training Program, and CANDAC for continuing to financially and logistically support the Canadian Arctic ACE/OSIRIS Validation Campaigns. Without this support, these campaigns, measurements, and learning opportunities would not be possible.

We hope that you have enjoyed reading about our visit to PEARL.

Cheers,
Darby Bates
[on behalf of the 2025 Canadian Arctic ACE/OSIRIS Validation Campaign team]